Prenatal diagnosis of cleidocranial dysplasia: Case report on two cases with a negative family history.

Introduction: Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia that presents with abnormalities in the craniofacial region, teeth, and clavicles and is linked to RUNX2 mutation. Prenatal diagnoses of CCD have rarely been reported, and most of these cases have a positive family history. Here we report two prenatally diagnosed CCD cases without a positive family history. We conducted a literature review to summarize the prenatal sonographic findings of CCD. Case reports: Case 1 (a 26-year-old woman): ultrasound at 13 weeks showed a thickened nuchal translucency with absent nasal bones and poor ossifications in the cranium and vertebrae. Genetic testing confirmed a frame shift deletion of RUNX2. Case 2 (a 27-year-old woman): ultrasound at 32 weeks showed potential fetal skeletal dysplasia, with inadequate skull ossification, mild ossified bilateral clavicles, and RUNX2 frameshift deletion mutation. Both cases were diagnosed with CCD and the parents chose pregnancy termination. Conclusion: These cases underscore the importance of sonographic examination for prenatal CCD diagnosis with a negative family history. By reviewing previous cases, we concluded that combining NB hypoplasia, clavicle and skull hypoplasia, and shortened long bones may be effective for early screening for CCD. Prenatal diagnosis is crucial for guiding medical decisions.